1) Field of the Invention
The field of invention relates to a method and apparatus for clamping used in molding applications. More particularly, the invention provides for a method and apparatus wherein a platen arrangement meets together perfectly, with minimal deflection, to produce an evenly formed part from the combination of two die or mold halves.
2) Description of Prior Art
The present invention is a method and apparatus for clamping used in molding applications. It may be used for injection molding, thermoforming, stretch blow molding, die stamping and the like.
In the prior art, a clamping apparatus for clamping a mold comprises molding halves disposed on a fixed board and a moving board. Such boards are mounted on tie bars and the moveable parts of the clamping apparatus are also mounted on such tie bars. An example of this is contained in U.S. Pat. Nos. 5,192,557 and 5,320,517.
Also, in the prior art, the mechanism which causes the rotational linear motion of the moveable platen for the mold is mounted on a plurality of tie bars. An example of this is contained in U.S. Pat. No. 4,984,980.
However, the lack of a mounting plate mounting the moving parts of the clamping device causes deflection and an uneven resulting molded part.
In the present invention the primary moving parts are mounted on a mounting plate. This allows for the clamping of the platens and applied force stresses created thereby to be dependent on the mounting plate rather than the tie bars. In other clamping devices or prior art devices, the applied force stresses are applied to the tie bars which cause deflection and an uneven molded part.